Tougher sentences should be imposed on garda killers, the widow of Detective Garda Jerry McCabe, who was killed by an IRA gang, has said.

Speaking ahead of a 20th anniversary commemoration concert in memory of the garda, Ann McCabe said the pain of losing her husband "will never go away".

She said the world was even more dangerous for gardaí since her husband's death in the village of Adare, Co Limerick, on June 7, 1996.

"It probably is, when you consider what's happening as late as in Dublin (on Tuesday) morning (referring to the murder of Gareth Hutch).

"But when they join the force, gardaí know what they are going into and that's their job, so it is very dangerous.

"But I think punishment should fit the crime and maybe longer sentences would be an option."

Pearse McCauley, Michael O'Neill, Jeremiah Sheehy and Kevin Walsh were charged with the murder of Detective Garda Jerry McCabe but the charge was dropped after key witnesses had refused to co-operate. They were then convicted of manslaughter.